The present invention relates to an image recording apparatus which forms an image on a copying medium such as ordinary paper with using a photosensitive recording medium.
An image recording medium is generally classified into a self-contained type recording medium and a transfer type recording medium. In the self-contained type recording medium, an encapsulated chromogenic material or dye precursor and a developer material are co-deposited on one surface of a single substrate as one layer or as two contiguous layers. The self-contained type is disclosed in U.S. Pat. No. 4,440,846.
In the transfer type recording medium, the developer material is coated on a separate substrate as a separate developer or copy sheet. The transfer type is disclosed in U.S. Pat. No. 4,399,209. More specifically, the transfer type image recording medium comprises a microcapsule sheet (first image recording medium) and a developer sheet (second image recording medium . The first image recording medium comprises a photosensitive pressure sensitive recording medium provided with microcapsules which encapsulate therein a first material (chromogenic material or dye precursor) having first and second phases dependent on light exposure. The second image recording medium comprises the developer medium provided with a second material (developer material) which provides an output image upon reaction with the first material. Further, image recording method employing photosensitive recording medium is also disclosed in Japanese Patent Application Kokai Nos. 61-137749, 61-143738 and 61-173981.
The photosensitive recording medium which is used for such image recording methods has a surface carrying thereon the photosensitive microcapsules which encapsulate therein the chromogenic material (the first material. When the photosensitive recording medium is exposed to light in accordance with an image information, the microcapsules exposed to light are hardened for increasing their mechanical strength, whereas non-exposed microcapsules remain intact for maintaining their low mechanical strength. After the light exposure, a developing medium carrying the developer material (the second material) which can cause a chromogenic reaction with the dye precursor is laid over the microcapsule surface of the photosensitive recording medium and these are pressed together. By this pressure, the microcapsules having the lower mechanical strength on the microcapsule sheet are ruptured for allowing the chromogenic material to flow out of the microcapsules. Therefore, the chromogenic reaction takes place between the outflowing dye precursor and the developer material, &o thereby form a visible image on the developing medium.
However, conventionally, it has been necessary to use the developing medium which is produced by a paper making company and it has been impossible for the user to freely use various kinds of papers for forming the visible output image thereon. In other words, in case of the transfer type image recording method, always required are the specific developer sheet mediums which are provided with the developer material on their surfaces.
Further, there has been another image recording apparatus which uses a photosensitive pressure sensitive image recording medium and a mask member. More specifically, when a combined image consisting of a picture image and character image is to be formed on an identical copying sheet, dual exposures have been made by a photosensitive pressure sensitive recording process. That is, two types of mask members are prepared for independently masking the picture image region and character image region. When the exposure with respect to the picture image region is carried out, a first mask member is placed over the character image region, and when the exposure with respect to the character image region is carried out, a second mask member is placed over the picture image region. Therefore, dual exposures must be required while one of the mask members is precisely placed on the intended position for masking.
According to this method, the positional alignment of the mask member requires much skill. Further, since the mask members are placed over the picture image region and character image region of an original, it has been impossible to obtain a combined image in which a black or colored output character image is superposed on the output picture image region, though it may be possible to form a white-out zone (non-exposed zone with respect to the character image on the picture image region. Moreover, in the final output image, the character image is likely to lack clarity particularly in its edge portion, since a light reflected on or transmitted through the original is used.